Control system for automatic single-chamber compressed air brakes



S. KELER CONTROL SYSTEM FOR AUT MATIC SINGLE-CHAMBER COMPRESSED AIR BRAKES Dec. 1, 1953 3 Sheets-Sheet 1 Filed June 19. 1947 Dec. 1, 1953 s. KELLER 2,661,248

i CONTROL SYSTEM FOR AUTOMATIC SINGLE-CHAMBER COMPRESSED AIR BRAKES Filed June 19. 1947 3 Sheets-SheeI 2 Dec. l, 1953 s. KELLER 2,651,248

CONTROL SYSTEM FOR AUTOMATIC SINGLE-CHAMBER COMPRESSED AIR BRAKES Filed June 19, 1947 3 Sheets-Sheet 3 5MM/0 /ffLLER t OPNKBC Patented Dec. l, 1%.53

UNITED OFFICE CONTROL SYSTEM FOR AUTOMATIC SINGLE-CHAMBER CMPRESSED AIR BRAKES a Swiss company Application June 19, 1947, Serial No. 755,705

16 Claims. E

The rapid developments in the eld of rail transport and in particular the tendency to step up the travelling speeds of express trains, and to run an increasing number of express goods trains without increasing the distance apart of the distant signals, place increased demands on the braking equipment of the trains.

Therefore, the necessity for developing the automatic, compressed air brake in all its functions up to the limit of its capacity is becoming more and more apparent.

This is one of the main objects of the present invention.

It has for its more specific objects:

(a) To raise the transmission speed to the maximum value that can be practically achieved with compressed air brakes within the sensitivity limits hereinbefore set forth, this being effected independently of the nature of the braking, whether normal operational braking or rapid emergency brakingis required;

(b) To increase the injection speed for normal operational braking and to obtain an injection speed which is independent of the nature of the braking;

(c) To keep constant the pressure drop which is produced automatically by the control system in the main air pipe for the first operational braking stage, independently of the volume of the main pipe from which draw-od is effected so that even the inclusion of a number of wagons which include only transmission pipes cannot essentially influence the pressure reduction;

(d) To keep constant, for all operational conditions, the injection pressure into the brake cylinder, independently of the main pipe draw-oli volume;

(e) To keep constant the maximum pressure in the brake cylinder, independently of the piston stroke and of the volume of the auxiliary air reservoir;

(f) To adapt the braking to the load in goods wagons, or to produce a stronger brake application according to the speed in the case of the coaches of express trains, without the use of mechanical load interehangers or additional pressure transmitters in combination with a second brake cylinder and auxiliary air reservoir, so that, for example, the control system can produce two pressure stages, either by the movement oi a lever in the case of goods wagons or by any known automatic speed-dependent changeover in the case oi express train coaches, the same brake cylinder charging and discharging times-holding good for both the pressure stages CII (g) To make the sizes of the charging passages, which are adjustable by changing the throttle bores, so large that even the largest brake cylinder can still be filled in a very short time;

(h) To reduce the time for the charging of the empty reservoirs.

With the above and other objects in View there is provided, according to the present invention, a control system for automatic single chamber compressed air brakes comprising a maximum pressure limiting device, an accelerator including a Valve which is acted upon by the discharging main air, a draw-ofi restricting device including a valve having two elements which open and close alternately, a header unit including a valve which is acted upon by the auxiliary air pressure and by a spring pressure, a cut-off unit, a minimum pressure limiting unit, a charging unit and a triple pressure regulating unit for controlling the braking action, wherein these units are so combined and coordinated that on the one hand a rapid injection of the pressure fluid into the brake cylinder can be obtained and on the other hand the brake cylinder pressure can be varied in two stages the maximum values of which -are limited, the variation taking place in dependence upon the pressure in the main air pipe, no that the said valve of the accelerator respends initially to the small pressure difference obtaining between the main air and the auxiliary air upon the initiation of a braking action, while at the instant that the said valve is opened by a member connected with it, it is acted upon 3 by the discharging main air and is thereby held open, independently of the development of any further pressure diierence between the main air and the auxiliary air, until the discharge of the main air is interrupted, which is done either by the draw-on restricting device, which device upon a definite pressure drop in the main air pipe closes as a result of the pressure difference obtaining between its main air and the control air, or by a discharge cut-oir unit which coopcrates withvthe draw-off restricting device and which, in the event of there being an insuffi- -cient pressure difference between the main air and the control air, closes after a predetermined time interval as a result of the static pressure of the discharging main air itself, whereby the minimum pressure limiting unit is opened by a sudden static pressure which is produced by the discharging main air, which pressure, during the new of air, reaches a value which is greater "than the pressure diierence obtaining between the main air and the auxiliary air, and which also rises to the full main pipe pressure after the interruption of the main air draw-off by the action o the draw-01T restricting device and the opening of the said valveV thereof, whereby the commencement of the injection of the auxiliary air into the brake cylinder by way of the header unit coincides practically without delay with the response of the accelerator, and whereby the connection between main air pipe, the auxiliary air reservoir and the control air reservoir, as well as the connection of these reservoirs with each other, is interrupted by the cut-off unit as a result of astatic pressure which is produced by the auxiliary air in one chamber operating against a static pressure in another chamber, which static pressure, during the duration of the injection, is greater than the pressure obtaining in the brake cylinder, and vthe interruption of the said connection being maintained after the desired injection pressure in the brake cylinder has been reached by the action of this pressure.

One form ci such a control system will be described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 shows diagrammatically the arrangement of the valves, pipes and other elements of the system;

Fig. 2 is a cross-section showing a valve assembly to a larger scale;

Fig. 3 is a section through the setting Valve.

Figs. 4, and 6 are sections along lines N-IV, V-V and VI-VI of Fig. 3.

The air-control system comprises a number of chambers, reservoirs, valves and pipes, which are combined into units according to their function. 'Ihese units include a maximum pressure limiter I, an accelerator II, a triple-pressure regulator III, a drawoi restricting device IV, a cut-oir unit V, a header unit VI, a minimum pressure unit VII, a charging unit VIII, a setting valve IX, a brake cylinder charging time control X, a discharge interrupter XI, an auxiliary air reservoir H, a control-air reservoir St and a brake cylinder Br. These units are connected with one another by suitable pipes. In the following description those parts of the system which can be considered as units will first be described.

'Ihe maximum pressure limiter I consists of a chamber i which is connected to the main compressed air supply pipe L and which is separated from two chambers 4 and 5 by means of ldiaphragms 2 and 3. connected with one another through a passage 58 formed in a valve rod 8 which is connected with the diaphragms 2 and 3 and which transmits to the latter the pressure of a spring 1.

A fixed valve seat I I3 together with a movable valve body IG form a seal between the chamber 5 and a further chamber I2. This valve is acted on by a spring I I. Thus, during charging, compressed air from the pipe L can pass to the chamber 5 through the passage 58 in the valve rod 6. The chamber 4 is connected to a pipe I3 and is acted upon by pressure in the control reservoir through this pipe, as will appear more clearly hereinafter. The chamber I2 is connected through a throttling passage I4 with the cham'- The chambers I and 5 are l of a chamber I 6 which is connected by way of a pipe I'I with the chamber 5, a chamber I3 which is connected to the auxiliary air pipe I9, a small chamber 2E, a cylinder 2i and a chamber 22. The chamber I6 is separated from the chamber I3 by a diaphragm 23. Ihe seal between the chambers I5 and 20 is eiected by a valve 24, which is rigidly connected with a piston 26 and a valve rod 25 and which is acted upon by a spring 21. There is no rigid connection between the valve rod 25 and the diaphragm 23, so that the movements of the diaphragm 23 can only act in one direction on the valve rod 25. The chambers 20 and 22 are separated from one another by means of a piston 25, except that there is a permanent annular clearance space between the piston 26 and the cylinder ZI. The chamber 22 is connected by means of a pipe 28 with the draw-oir restricting device IV.

The triple-pressure regulator III comprises two chambers 29 and SEI, which are separated from one another by a diaphragm 3 I. The chamu ber 2Q is connected through a pipe 32 with the -chamber I6 and is under the influence of the air in the main compressed air supply pipe L through the pipe I'I and the maximum pressure limiter I, whilst the chamber Z is under the iniiuence of the control air acting through pipes 33 and 34. The diaphragm BI is connected through a gland in the dividing wall 35 with a valve rod 36 which is formed with an axial bore. Between the wall 35 and a further diaphragm 37, there is the space 38, which may be connected to atmosphere through a pipe 39 under the control vo1' the setting Valve IX. The bore of the valve rod 3G opens into the chamber 38.

The diaphragm 37 and another diaphragm 4D are connected with the valve rod 36. Above the diaphragm 3.' is the chamber 4I which is connected either with the chamber d2 above the diaphragm QI! or to atmosphere. A pipe 43 leads from the chamber G2 to a speedcontrolled unit U and through the charging time control unit X to the brake cylinder Br. The valve rod 36 and the diaphragme 4I), 37 and 3! connected therewith are acted upon by a springI 47 which maintains a gap (IB through which the bore in the valve rod 3G communicates with the chamber 42. The chamber M above the chamber 42 is separated from the latter by a valve 46 which is acted upon by a spring d5. The chamber 44 is connected with the auxiliary air reservoir I-I by the pipe 9, the setting valve IX, and the pipe 'I.

The draw-on? restricting device IV comprises a chamber 56 which is connected with a control air pipe 5I. Above the chamber 59 is a chamber 52 which is connected with the chamber I6 of the accelerator II by means of a pipe 53. The chamber 5G is separated from the chamber 52 by a diaphragm 54 which is under the action vof a spring 59. Connected with the diaphragm 512 is a valve rod 55 which carries two valve bodies 56 and I I 2.

The chambers 52 and 57 are separated from each other by the lower valve body I I2. The port controlled by the upper valve body 56 leads to atmosphere, as will be later described, through the space I2! of the discharge cut-off unit XI. The chamber 51 is connected by a pipe 6i] with the header unit VI and by the pipe 28 with the chamber 22 of the accelerator II.

The cut-o` unit V comprises three chambers 6I, 62 and 53. Into the chamber 5I there opens a pipe S4 which is connected with the compressed air supply pipe L through the 'pipe andthe maximum pressure limiter The control air pipe t5 leads from the chamber iii and is opened or closed simultaneously with the pipe iid by the valve 5S. An auxiliary air pipe @i3 branches ozt from the chamber' 6| through the sensitivity passage 5l. The valve 6% is connected with the diaphragms 'it and l' by means of a valve rod te. The chamber t2 between these two diaphragins communicates with atmosphere. The chamber tft communicates through the pipe l2 with the minimum pressure unit Vil.

The header unit "Il comprises the chambers lil, it and lli. The chamber i3 is connected through a pipe l with the auxiliary air reservoir i-I and is shut oil om the chamber ill by the valve 'i8 which is under the pressure of spring il. The chambers ifi i5 are separated from one another by a diaphragm til, which is connecte with the valve 'is by means of a valve rod '|9. The chamber 'iii is connected with the chamber 82 of the in: imam pressure unit VII by a pipe 8|.

The minimum pressure unit VII comprises the chambers ti and the chamber S5 which communicates with atmosphere. The chamber is separated from the chamber 85 by a til. A valve rod is connected with the diaphragm t?. This rod passes through the dividing wall 39 into the chamber 83 and carries a valve The latter is held in the open position by the pressure of a spring Sil. The chamber se is connected by a pipe @i with a Venturi nozzle 92, which is inserted in the brake cylinder pipe |33 and produces a negative pressure in the chamber tft during t .e dow of the air.

The charging unit Vlll comprises chambers 9e, 95 and l5. The chamber 94, which is separated from the chamber @Si by a diaphragm Sti, subjected to the pressure of the control air through the pipes i3 et. nected a pipe with the auxiliary air reservoir H. The chambers i5 and S5 are separated from one another by a valve plate S3. The valve plate @il is connected with the diaphragm s6 by means of a valve rod Sii and is acted up by a spring itt. The charging unit VIII communicates with the chamber l2 of the maximum pressure limiter by way of the throttling passage ifi.

The setting valve XX, which is shown in detail in Figures l, 3; e, 5 and 6 comprises an inner friction cone lill, in which are formed tivo separate axially-spaced sets of charging passages H3 and lili and discharging passages H5 and iid respectively, which correspond to the different charging and discharging times required with different types of Tora-kes (such as on goods trains, ordinary passenger trains and express trains). Afiially spaced from these passages it is formed with a gro-ove l il', which is connected with atmosphere. rEhe setting valve also comprises an outer friction cone iii which is rotatably mounted in the housing i i lo of the device, which cone l actuates in a first position the charging passages i3 and the discharging passages 5 and in a second position interrupts this connection and opens the charging passages H4 and the discharging passages iit. The outer cone also has a bore |39 through which the conduit 8 is connected with the bore i il in the inner cone Hl, as well as groove itil by means of which the conduits and 9 may be connected with each other. in the first position the chamber dl is connected with the atmosphere through the conduit d and the bores |39 and |7, while the con- The chamber 95 is con- 6 nection of' the conduits 8 and' 9 through the groove I 40 is interrupted. On the other hand, in the second position, the connection of the conduit 8 with the bore Il is interrupted, while the chamber 6| is connected through the groove |40 and the conduit 9 with the speed regulator U. The unit U includes two valves |35 and |32 which are operated jointly by means of the valve rod |33. A magnetic winding |3 is included in a circuit which contains a contact |36 and a battery |37, the contact |36 being actuated by a centrifugal regulator |38. At small speed the contact |36 is open, so that the magnetic winding |34 will not be energized. Then the valve rod |33 is situated in the position shown in the drawing, wherein the valve |3| is open While the valve |32 is closed and the conduits 9 and t3 are interconnected. At high speeds, on the other hand, the Valve |3| is closed and the valve |32 is open, so that the connection of the conduits d3 and 9 is interrupted. Furthermore, the conduit 9 is connected with the atmosphere through the valve |32. Thus by means of the inner friction cone ||0 the device can be set depending upon the type of train, namely, whether it is a goods train G, passenger P, or express S, while by means of the outer friction cone it is possible to set diilerent braking pressure stages. When the outer cone is located in the aforesaid second position, in which the lower pressure stage is operable, the upper pressure stage becornes elective at great speed by energizing the magnet winding |34, in that the chamber l is discharged through the conduit 8, the groove |56, the conduit 9 and the Valve |32.

The unit X for limiting the charging time of the brake cylinder comprises chambers il, |02, |53 -which are separated from one another by means of diaphragme |84 and |95. The chambei' |132 is permanently connected with atmosphere. The two diaphragms are connected together by a valve rod |535 which extends beyond the diaphragm it in the form of a tube. The end of this tube has the form of a valve seat lill provided with a restriction passage |68 and having an opening toward the chamber |3. When the valve is closed, the brake air owing from the triple-pressure regulator III by way of the pipe i3 can only new to the brake cylinder Br through the valve rod ii and through the throttling passage |03 in the valve plate |07 by way of the pipe G9.

The discharge cut-ofi unit XI consists of a chamber |25, which is connected on the one hand with a compression chamber |22 through a throttling passage |27 and a pipe |28 and is connected on the other hand, by way of a valve it, with a space |23 which is open to atmosphere. The valve |213 prevents to a small eX- tent in its open position the free now of compressed air from the chamber |2| to the atmosphere and thus produces a baffle eiect in that chamber. Connected in parallel with the valve |243 is a small, permanently opened air-discharge passage l. The passage iti) is required to provide an outflow into the atmosphere of the compressed air from the chamber |22 through the pipe |28 and the opening of the passage |33 after the closing of the valve |24. The compression chamber |22 is separated from the chamber |23 which is connected with atmosphere through 'iis with the valve |24 and isunder the action of a spring |26;

7 The units just descrihedmay be arranged .in one or more housings, according to the space available on the wagon or locomotive. Thesequence of operations during the charging of the empty reservoirs, during braking and during the oer 5. Hence it passes through the pipes i1 `and 64 into the chamber 5l of the cut-off unit V. Owing to the pressure thus exerted on the diaphragm I0, the valve 66 is lifted from its .seating. The air can now iiow through the pipe 65 to the control reservoir St, to 'which is connected a throttling passage H26, so that practically the unthrottled main pipe pressure is obtained in the pipe '65 and in the control chambers 50, 30, Sli and d which are connected with it by means of the pipes 5 l, 3a, 33 and i3.

From the chamber Si the compressed air also flows through the sensitivity passage 6T and the pipe 6B to the auxiliary reservoir H. Because of the throttling caused by the said passage 6I, the pressure in the auxiliary air part of the control system is less than that in those control chambers which are connected in front of the throttling passage IEB of the control reservoir St.

As a result, the diaphragm 96 of the charging unit VIII lifts the valve 98 against the pressure of the spring,r lei! and thus produces a connection between the chambers l5 and S5, whereby the` pressure in the chambers l2 and i5 is ref duced to the pressure in the auxiliary air reservoir H. The compressed air coming from the pipe L can now also lift the valve IG against the action of the spring H and can flow into the auxiliary air reservoir by way of the throttling passage ifi, the chamber l5 and the pipe 91. In this way, the time for the initial charging is greatly reduced, so that the object set forth at (ai in thc opening part or this specication is achieved.

The spring 505 of the charging unit VIII is so adjusted that this valve cioses as soon as the auxiliary pressure is about 0.2 lig/cm.2 lower than the control pressure. The rest of the charging thereupon takes place solely by Way of the chamber ft2 and thus into the brake cylinder is prevented by the valve 46 which is in the closed position. The auxiliary air reaches the chamber i8 of the accelerator II through the pipe i9 and reaches the chamber 13 of the header unit VI by way of the pipe 18. Further passage of the air to the brake cylinder is prevented by the valve 18.

If the reservoirs and. chambers should be momentarily overloaded by too high a pipe pressure during the initial stages, an independent equalisation of pressure takes place through the valve 66 of the open cut-off unit V, until the same pressure obtains, upon completion of the charging, in all reservoirs and in the chambers connected therewith. AIn this connection, the following are evacuated: the brake cylinder Br (through the pipe 109, chamber H33, pipe 43, chamber 42, the hollow valve rod 36, the chamber 33 of the triple-pressure regulator III, the pipe 39 and the corresponding discharge passage of the setting valve IX which leads to atmosphere) the chamber 63 of the shut-off unit V, the chamber 83 of the minimum pressure unit VII and the chamber 'i4 of the header unit VI (which is connected by way of chamber 83 and pipe 93 with the brake cylinder, which is evacuated in the manner already set forth). The chambers 2D and 22 of the accelerator l1, the chamber 51 of the draw-ofi control unit IV and the chamber 'l5 of the header unit VI connected therewith are connected with atmosphere through the open valve 56 of the draw-off control unit IV. All the chambers of the discharge cut-off unit XI are also evacuated.

Braking takes place in the following manner: If the necessary pressure drop for initiating the braking is produced in the main pipe L by hand or by mechanical means, the main pipe pressure in the chamber i6 of the accelerator II, owing to the action of the sensitivity passage $1 in the sensitivity unit V, drops somewhat more quickly than does the auxiliary air pressure in the opposing chamber IB, whereupon the diaphragm 23 lifts the valve 24 (Figure 2) from its seat in known manner. Thus the main air can suddenly discharge to atmosphere through the chambers 2E and 22 of the accelerator II, through the very small chamber 51 of the drawofi control unit IV and through the valves 5G and 124. As already stated, the valve |24 prevents in its open position the compressed air from freely flowing to the atmosphere and thus produces a baille effect in the chamber !2I. The valve H2 operates in the same manner so long as it is open so that a baille eiect is also created in the chamber 5l. In this way, there is inomentarily produced, at the commencement of the draw-off, a very high static pressure in the small baille chamber 5I which is connected with the chamber l5 of the header unit VI, the latter chamber also being very small. Under this static pressure, the diaphragm Sli suddenly opens the valve I3, whereupon the auxiliary air can iiow very rapidly and with little resistance into the brake cylinder Br by way of the chamber 'M and pipe 8| and through the minimum pressure unit VII.

If the desired header pressure is reached for the application of the brake shoe, then the valve 8S closes, because of the charging pressure on the diaphragm 81, against the action of the compression spring SB. The connection of the auxiliary air reservoir to the brake cylinder by way of the pipe 93 is thus interrupted. With the openingr of the header unit, a substantially higher static pressure is formed in the very small bafiie chamber 83 of the minimum pressure Unit VII` during the period of ow, as compared with the pressure in the brake cylinder, and this static pressure is transmitted through the pipe 'I2 to the chamber 63 of the cut-olf unit V, whereupon the diaphragm 7l suddenly forces the valve 66 on to its seating. This interrupts the connection between the main air pipe B4 and the auxiliary air reservoir I-I and the control air reservoir St and also interrupts the connection between the pipes and chambers connected thereto.

Actually the operations described above in sep- Mate Stages take place very quickly, so that the application of the brake shoe and interruption of the connection between the individual reservoirs practically coincides with the beginning of the draw-off through the accelerator. Thus in practice, even though the sensitivity passages 6'! and I 2G are relatively large no air can flow back into the main air pipe,

These first operations are initiated immediately and independently of the nature of the braking that is required, from the minimum operational braking to emergency braking, because they are directly caused by the static pressure of the discharging main air. Thus the objects (d) and (b) are achieved.

Immediately upon the response of the accelerator II, the pressure changes in the main air parts of the system and in the auxiliary air parts can continue completely independently of one another. In particular, the draw-oir from the main air pipe by way of the draw-01T control unit IV continues irrespectively of the volume of the main pipe, which volume depends on the number of pipes connected, until the main air pipe pressure has fallen to the value required for the first stage of the braking. Then the pressure difference occurring between the chamber t, which is in communication with the control reservoir St, and the chamber 52, which is in communication with the main air pipe, overcomes the spring a'i. rEhe upper valve body H2 is forced on to its seat and the connection of the main air pipe with the surrounding air is interrupted.

The independence of the changes in the pressures of the main and auxiliary is obtained by the novel accelerator construction as shown in Figure 2. The valve or the accelerator II is constructed as a very small, light piston 2S which moves with the minimum of friction in the bore of the cylinder 2i, there being an annular airspace which has a definite relationship to the cross-section or ilow area of the valve opening.

.at the moment that the draw-off from the chamber le and the main pipe connected therewith begins, a momentary high static pressure is formed in the very small chamber 2li, whereby the piston 2l is raised to the height of the discharge opening 2li. The piston remains oscillating in this position so long as the discharge through the open valve 5E of the draw-off unit IV and the open valve ld of the discharge cut-off unit XI continues, this being completely independent of the further development of the pressure in the chambers U5 and i3 of the accelerator Il'. The object (c) mentioned in the earlier part i this specincation is thus achieved.

cross-sectional area of the valve 'i8 of the header unit VI may thus even be made so large that the pressure drop in the auxiliary air reservon` proceeds in advance oi that in the main pipe without thereby interrupting the draw-oit, since in this case the valve rod E5 of the accelerator II cannot follow the downward movement of the diaphragm However, as soon as the ow is interrupted by the correct closing of the upper valve 5t of the draw-oit unit IV, the spring 21 forces the oscillating piston 26 back again and thus forces the valve 2d on to its seat.

In the opposite case, i. e., when the main pipe volume to be drawn-ou is small in comparison with the header volume of the brake 'cylinder and thereiore the discharge from the main pipe has nished before the header pressure in the brake cylinder has reached the prescribed value, the full main pipe pressure is produced in the of the minimum pressure unit VII.

chamber 5'! of the draw-olf unit IV and in the chamber 'i5 of the header unit VI which is connected therewith by Way of the pipe 60, because of the connection of the chamber 5l with the chamber 52 by way of the lower valve which is now lifted. Under this pressure on the diaphragm Si), the valve i8 is still held in the open position, so that the charging can continue until it is in due course interrupted by the operation In this manner, the object (d) is achieved.

In order to prevent the minimum pressure unit VII from being prematurely cut on by the static pressure obtaining in the control system, which pressure is relatively high in comparison with the brake cylinder pressure, the chamber fi is connected with a barile nozzle 92 which is in the braking air passage and produces a negative relative pressure. So long as the ilow continues (due .to the movement of the brake piston until the application of the brake shoe) a smaller pressure obtains in the chamber Sil than in the brake cylinder.

At the instant the movement oi the brake piston ends, a back pressure is produced in the pipe d3, whereupon the pressure in the chamber 8i rises suddenly, the diaphragm 8? overcomes the spring 9L and thus brings the valve B to its closed position. At this moment of the interruption of the flow, the pressure in the small chambers 82 and le rises immediately up to the pressure in the auxiliary air reservoir, whereby the diaphragm Si] is forced upwardly and the valve 'i3 also returns to its closed position under the action oi the spring il. The area of the valve Sii, which is now under its auxiliary air pressure, is so chosen that the spring Si) is only capable of opening again when the brake cylinder pressure has sunk below about 0.3 kg./cm.2, i. e., only upon complete release of the brake.

Unailected by the charging action, the triplepressure regulating unit III has moved to the cutoff position, because of the pressure difference between the chamber 3i), which is under the control pressure, and the chamber 29, which is under pipe pressure. Upon a further pressure drop in the main air chamber 253, the valve 5 is lifted, the auxiliary air reservoir I-I can flow to the brake cylinder Br by `way of corresponding charging bores in the setting valve IX and through the pipe 13.9, the chambers lil and 2, the pipe 153, the chamber i533 and the pipe H39. rl`he brake cylinder pressure produced in the chambers i2 or lll counteracts the pressure difference obtaining between the chambers 2i) and 39, and thus it is possible, in known manner, to produce any desired braking or releasing stages by varying the main pipe pressure.

By the selective inclusion of the chambers 52 or di, the eiective cross-sections of which are different, the brake cylinder pressure which corresponds to a given main pipe pressure may be made larger or smaller. The inclusion or bypassing or' the chambers is effected through the special setting valve IX, by the action of which suitable larger or smaller charging and discharging passages, which may be interchangeable as desired, are simultaneously connected in. the systern, with the object of keeping the ybrake cylinder charging or discharging times for the positions G, P and S the same for both pressure stages. This arrangement allows goods Waggons, both in normal goods trains and also in express goods trains, to be braked to varying degrees, whether whereupon further compressed air from empty or loaded, using position P, or express goods trains to be braked to varying degrees in dependence upon the travelling speed, without using a mechanical load change over in the case of goods Waggons or using a second brake cylinder or a special pressure transmitter in the case of express trains.

The flow area of the triple pressure regulator valve 46 for the charging of the brake cylinder in the position S is suicient to ensure that even the largest brake cylinder is charged up to the maximum pressure in the prescribed minimum time. The special unit X for limiting the charging time of the brake cylinder also provides, as hereinafter set forth, for the automatic introduction of a smaller charging passage for the emergency braking of an express train at a speed below the speed range which is operative for normal quick braking.

Thus, for example, if by the action of the speed-controlled change-over valve U, the chamber 4| of the triple-pressure regulator is evacuated, i. e., the high pressure stage is introduced, then the space iti of the charging time control unit X is also evacuated. The brake pressure acting in the chamber |63 on the diaphragm |85 lifts the valve il'i from its seat, thus allowing the free flow of the compressed air coming from the triple-pressure regulator III by way or" pipe 43 but only through the corresponding charging bore in the setting valve IX.

However, if the low pressure stage is introduced, the brake pressure also occurs in the chamber |I, whereupon the diaphragm lee, which has a larger effective area, overcomes the pressure exerted by the opposing diaphragm ISE. The valve I 01 is thus forced on to its seat, whereupon the compressed air may only now to the brake cylinder by way of the correspondingly smaller charging passage I B of the valve |01, so that the lower pressure is reached in the same time as the higher pressure. In this manner, the objects (f) and (y) are achieved.

In order to limit the brake cylinder maximum pressure to the permissible value for every contingency likely to occur, and in order to obtain this substantially independently of the stroke of the brake piston and of the volume oi the auxiliary air reservoir, that part of the control system which is under the main air pressure is connected to the main air pipe L by way of the maximum pressure-limiting unit I. As soon as the pressure drop in the main pipe becomes greater than is necessary for producing a full application of the brake, e. g., greater than 1.5 kg./cm.2, whether it be by a slow lowering of pressure or as a result of a quick application of the brake, then the maximum pressure limiter I interrupts the connection with the main pipe L in that the pressure dilerence forming between the chambers and 4 overcomes the spring 1, whereupon the hollow valve rod 5 is forced against the valve il) and so interrupts the connection between the main air pipe and the remaining part of the air-control system.

Should it happen that, because of a quick application of the brake or because of slight leakages in the main .air part of the control system, the pressure in the chamber 5 sinks to below the permissible value, e. g., below 3.5 kg./cm.2, then the pressure difference between the chambers `5 and 4 further increases, whereupon the valve I0 is lifted and immediately there takes place a charging action from the auxiliary air reservoir I-Iby way of the valve 98 (which is now open because of the lowered auxiliary air pressure) of the charging unit VIII.

Conversely, if the maximum pressure limiter allows too high a pressure to develop in the chamber 5 and thus in the other chambers connected therewith, the valve rod 6 is retracted from the Valve IS under the action or" the diaphragm 3 and the spring 1, whereupon the excess pressure is immediately released through the pipe L and through the bore in the valve rod 6. In the event of a leaky brake cylinder, the valve 4E is lifted by the valve rod 35 because of the pressure drop in the chambers e! or 132 of the triple pressure regulator, whereupon there is a continuous ow from the auxiliary air reservoir of that amount of compressed air which is necessary for maintaining the brake cylinder pressure. If, as a result of this discharge, the pressure in the auxiliary air reservoir sinks below the pressure in the main pipe L, then the valve I0' of the maximum pressure limiter I opens, and the auxiliary air reservoir is fed by way of the passage llt, the chamber l5 of the open charging unit VIII and the pipe S'. In this manner, object (e) is achieved.

The discharge cut-oir unit XI is provided to cover, for example, trains in which there is an excessive leakage in the coupling elements of the main air pipe or the breakage of the air control system during shunting, in which cases the discharge by way of the draw-off limiter IV cannot be interrupted in the manner described, because of the pressure regulator of the drivers brake valve continuously supplying as much compressed .air into the main pipe as is passed out by Way of the accelerator; in other words, the pressure dilerence between the main air chamber 52 and the control chamber 5B, which is necessary for cutting-off of the draw-oil limiting unit IV is not obtained.

In this case, the pressure chamber |22 is charged, by way of throttle passage |21 and the pipe |23 trom the chamber t2 which is under the pressure of the discharging main air. The

f time taken to charge up to the static pressure is,

in this case, an exact function of the ratio between the volume of the pressure chamber |22 and the crosssection of the throttle passage |211.

If the pressure in the pressure chamber |22 exceeds a certain value, then the diaphragm |25 overcomes the force of the spring |26, whereupon the valve |23. closes. Owing to the interruption of the flow, the pressures above and below the piston 23 of the-accelerator Il'. are immediately balanced, whereupon the valve 2e is again closed by the action of the spring 2. The compressed air can now again escape from the chamber |22 to atmosphere by way of thepipe i518, the throttle passage i2?, the static chamber ili and the airescape passage |30. The valve Hill thereupon opens again and the air control system is again ready for operation.

rEhe charging time for the pressure chamber |22 is advantageously so selected that with goods trains, for example, the volume of i5 to 2Q lead* ing unbraked Waggons can be drawn oil i'rom a single air control system for the rst operational braking stage before the discharge cut-ofi unit XI functions, whereas 'this time interval can be made shorter with passenger trains.

Instead of the spring |26, it is also possible for a static pressure to be used to apply pressure to the diaphragm |25, such static pressure beingy preferably adjustable in accordance with the ratio between the cross-sectional areas of the valve i213 and the discharge opening leading to atmosphere.

The release of the brake takes place in the following manner: If the pressure in the main air pipe L, and thus also in the chamber 29 of the triple-pressure regulating unit III, increases, then the hollow valve rod 36 moves downwardly, whereupon compressed air from the brake cylinder BT passes into the chamber 33 and pipe 33 by way of the pipe i' e, chamber A93, pipe d3 and the hollow valve rod Sit; it then escapes to atniosphere by way of the corresponding release or discharge bore ci the setting valve IX.

If the pressure rise in the main air pipe is interrupted before the normal operating pressure is reached, then the eventual brake pressure is set at a lower value corresponding to the new main pipe pressure. In this way, the brake may be released in stages in known manner.

If the releasing of the brake taires place after a quick application of the brake, in which the maximum pressure limiting unit I has been in operation, then first of all the connection through the hollow valve rod 6 is again produced by the action of the pressure rise, whereupon the release operation proceeds as previously described. If, during the release, the main air pressure rises to a definite amount above the auxiliary air pressure, then the valve i il is lifted against the spring l, whereupon air from the main pipe L can iiow into the auxiliary air reservoir l-I by way of the charging unit VIII and the pipe 97. The unit VIII is so adjusted that it closes as soon as the auxiliary air pressure has reached a value within about 0.2 lag/cm.2 of the control pressure, thus rendering further charging impossible, even with high and long charging impulses.

As soon as the main pipe pressure has reached the value (e, g., 4.6 kg./cm.2) required for the nrst braking stage, the upper valve t of the draw-oil limiting unit IV opens under the action of the spring 59 and thus evacuates the air from the chambers l, 22 and 2li of the accelerator II, as well as from the chamber 'l5 of the header unit VI. If the main pipe pressure rises still further, then the brake pressure sinks even more because of the action of the triple-pressure regulating unit III until finally, with a brake cylinder pressure of about 0.3 lig/cm?, the auxiliary air pressure on the diaphragm it of the cut-off unit V overcomes the brake cylinder pressure on the larger opposing diaphragm 'l I, whereupon the valve 66 is lifted from its seat, a connection between the reservoirs again being produced, whereupon the brake is completely released.

The auxiliary air reservoir may now be completely charged by way of the sensitivity passage 6l. Finally, the minimum pressure unit also opens again.

It will be understood from the operation described that upon releasing the brake, high charging impulses having a duration equal to that of the brake releasing time (which may in position F, for example, be of the order of 45-50 seconds) can be applied without the reservoirs being overloaded, i. e., until the pressure in the brake cylinder has sunk to about 0.3 liga/cm?.

I claim:

l. A control system for automatic, singlechamber, compressed air brakes, comprising a maximum-pressure-limiting device containing a spring-actuated valve and a diaphragm, whereby the interior of said device is divided into at least rst, second and third chambers, an accelerator containing a discharged-air and spring-actuated valve whereby the interior of said accelerator -i's' divided into at least rst and second chambers, a draw-off, restricting device containing a springactuated valve having two elements which open and close alternately, the interior of said drawoi, restricting device comprising at least iirst and second chambers, a header unit containing a diaphragm and an auxiliary-air and spring-actuated valve connected with the last-mentioned diaphragm, the interior of said header unit being divided by said diaphragm and said valve into at least rst, second and third chambers, a cut-off unit containing a diaphragm-actuated valve, a minimum-pressure unit containing a valve, the interior of said minimum-pressure unit being divided into at least first and second chambers, the second chamber of sad minimum-pressure unit being connected with the second chamber of said header unit, a charging unit containing a spring-loaded valve and a diaphragm connected therewith, whereby the interior of said charging unit is divided into at least rst and second chambers, a triple-pressure, regulating unit containing a spring-actuated valve and diaphragms dividing it into at least iirst, second and third chambers, a brake cylinder, a main air pipe connected with the second chamber of said maximum-pressure-limiting device, an auxiliary air reservoir, a control-air reservoir, a discharge interruptor connected with the second chamber of said daw-off, restricting device, and the atmosphere, a second pipe connecting the second chamber of said maxiinum-pressure-limiting device with said cut-on unit, means connecting the first chamber of said maximum-pressure-limiting device with the first chamber of said charging unit, a third pipe connecting the third chamber of said maximum-pressure-limiting device with the second chamber of said charging unit, a fourth pipe connecting the iirst chamber of said charging unit with said control-air reservoir, a fth pipe connecting the fourth-mentioned pipe with the ilrst chamber of said triple-pressure, regulating unit, second means connecting the third chamber of said triple-pressure, regulating unit with said brake cylinder, a sixth pipe connecting the rst chamber of said minimum-pressure unit with said brake cylinder, a seventh pipe connecting the first chamber of said header unit with said auxiliary air reservoir, an eighth pipe connecting the second chamber of said triple-pressure, regulating unit with the first chamber of said accelerator, a ninth pipe connecting the second chamber of said accelerator with the second chamber of said drawoff, restricting device, and a tenth pipe connecting the iirst chamber of said draw-01T, restricting device with the third chamber of said header unit.

2. A control system according to claim l, wherein said accelerator further contains a diaphragm which separates the first chamber of said accelerator from a third chamber, and which is adapted to engage and operate the spring-actuated valve of said accelerator, and an eleventh pipe connecting the third chamber of said accelerator with the seventh-mentioned pipe extending between said auxiliary air reservoir and the rst chamber of said header unit, whereby the spring-actuated valve of said accelerator is actuated by the diierence between main air pressure and auxiliary air pressure.

3. A control system according to claim l, wherein said draw-01T, restricting device further includes a diaphragm connected to the spring-actuated valve of the draw-off, restricting device aaa-1,2548

i5 and located in an additional chamber: formed therein, and a twelfth pipe connecting said. additional chamber or" the draw-off, restricting device with the fourth-mentioned pipe, the alternatel opening and closing of said two elements of the valve of said draw-on, restrictingV device being caused by the pressure difference. .between main air and control air.

4. A control system according to claim l, wherein said discharge interruptor. is connected with the second chamber of said draw-off, restricting device through a throttling passage of predetermined cross-section and includes a diaphragm and a valve connected therewith, whereby said discharge interruptor is divided into rst and second chambers, the second chamber thereof of predetermined volume communicating with said throttling passage, while the first chamber is open to the atmosphere and is in communication with the second chamber of said draw-off, restricting device when the valve of the discharge interruptor is open, and a spring engaging the last-mentioned valve and adapted to hold it open during discharge.

5. A control s 'stem according to claim 4, com-r prising a thirteenth pipe connecting the iirst chamber o said accelerator with the iirst chamber of said draw-off, restricting device, and a fourteenth pipe connecting the rst chamber of said accelerator with the second chamber of the maximum-pressure-limiting device.

6. A control system according to claim 5,.where in said cut-off unit includes two diaphragme connected with the valve of the cut-ofi unit, whereby the interior of said cut-01T; unit is divided into rst, second and third chambersand wherein said minimum-pressure unit includes a diaphragm connected with theV valve of the minimum-pressure unit and a dividing wall located between the diaphragm and the valve, whereby at least one additional chamber is iorined in the interior of said minimum-pressure unit, the valve of the minimum-pressure unitconnecting the second chamber of said header unit with the rst chamber of the minimumepressure unit, a fifteenth pipe connecting the rst chamber of the minimum-pressure unit with the third chamber of the cut-oii` unit, the second chamber of the cut-off unit and the additional chamber of the minimum-pressure unit being open to the atmosphere, a sixteenth pipe connecting the rst chamber of said cut-oir unit with the fourth-mentioned pipe, andY third means connecting the second chamber of the charging unit, with the auxiliary air reservoir, whereby the valve of the cut-off'unit is adapted to interrupt the connection between the main air pipe and the auxiliary air reservoir or the control-air reservoir.

7. A control system according to claim 6, comprising a suction member located in the sixthmentioned pipe, said minimum-pressure unit having a second additional chamber between the diaphragm and the dividing wall, and an eleventh pipe connecting the sixth-mentioned pipe with the second additional chamber. of the minimumpressure unit, said minimum-pressure unit containing a spring located in its first additional chamber and engagingl the diaphragm thereof to maintain open the valve of the minimumpressure unit.

8. A control system according to claim 6, wherein the third-mentioned pipe comprises a sensitivity-passage formed therein, and wherein the fourth-mentioned pipe comprisesa throttling passage formed thereiny and located close to the inlet of said control-air reservoir, and wherein the spring of the spring-loaded valve of said charging unit is of such strength that pressure difference between main an` and auxiliary air causes said spring-loaded valve to open during the charging of the empty reservoir from the main air line.

9. A control system according to claim 1, cornprising a setting valve operatively connected with said triple-pressure, regulating unit and comprising two cooperating members movable relatively to each other, and a housing containing said members, one of said members having two passages formed therein for adjusting different pressure stages, the other one of said members having air-controlling passages for regulating charging and releasing times, and throttle sleeves for said passages, said throttle sleeves being di mensioned to provide required charging and releasing times.

10. A control system according to claim l, wherein an additional chamber is formed in said charging unit between the valve and the diaphragm thereof and comprising an eighteenth pipe connecting said additional chamber with said :auxiliary air reservoir, and wherein said triple-pressure, regulating unit has an additional chamber containing the spring-operated valve thereof, and means connecting the last-mentioned additional chamber with the eighteenth mentioned pipe, whereby said auxiliary air reservoir is connected with the valve of the maximum pressure-limiting device and the main air pipe, and wherein said maximum-pressure-limiting device includes a hollow valve rod and a diaphragm connected therewith, whereby an additional chamber is formed in said maximumpressure-limiting device between said diaphragm and its valve, said hollow valve rod connecting said main air pipe with the additional chamber of said maximum-pressure-limiting device, the valve of the maximum-pressure-limiting device being operated by pressure difference between main air and control air.

11. A control system according to claim 1, wherein the second-mentioned means connecting the third chamber of said triple-pressure, regulating unit with said brake cylinder includes a charging time control unit having a throttling passage formed therein, a braking air pipe connecting said throttling passage with said brake cylinder, and a pipe connecting said charging time control unit with the third chamber of said triple-pressure, regulating unit.

12. In a compressed air brake in combination with a main air pipe normally having a predetermined operating pressure, and an air reservoir, normally charged to operating pressure; means connecting said main air pipe with the atmosphere and comprising a normally open rst valve and a normally closed second valve, means connected with the first-mentioned valve and closing the first-mentioned valve when pressure in the main air pipe drops to a predetermined extent, pneumatic actuating means for the second-mentioned valve connected with said air reservoir and responsive to a drop of pressure in the main air pipe below the pressure in said air reservoir to open the second-mentioned valve, and means connected with the secondmentioned valve for holding it open until the nrst-mentionedl valve is closed.

.13. In a compressed air brake in combination w1thal main air pipe normally having a predetermmedoperating pressure. and an air reservoir normally charged to operating pressure; means constituting a communication connecting said main air pipe with the atmosphere and comprising a normally open iirst valve and a normally closed second valve, said second valve having a movable part, means connected with the firstmentioned valve and closing it when pressure in the main air pipe drops to a predetermined extent, pneumatic actuating means for the second-mentioned valve connected with said air reservoir and responsive to a drop of pressure in the main air pipe below the pressure in said air reservoir to open the second-mentioned valve; an element movably disposed in said communication means and connected with said movable part of the second mentioned valve, said element forming a narrowed passage in the communication means t0 hold the second mentioned valve open under the influence of the air flowing through the passage until the first-mentioned valve is closed.

14. In a compressed air brake in combination with a main air pipe normally having a predetermined operating pressure, an auxiliary air reservoir and a control-air reservoir both normally charged to operating pressure; means constituting a communication connecting said main air pipe with the atmosphere and comprising a normally open rst Valve and a normally closed second valve, actuating means for the rst-mentioned valve subjected to opposing actions of pressures in the main air pipe and in the controlair reservoir to close the iirst-mentioned valve when pressure in the main air pipe drops to a predetermined extent; pneumatic actuating means for the second-mentioned valve connected With said auxiliary reservoir and responsive to a drop of pressure in the main air pipe below the pressure in the auxiliary air reservoir to open the second-mentioned valve; an element movably disposed in said communication means and connected with the second-mentioned valve, said element forming a narrowed passage in the communications means to hold the second-mentioned valve open under the influence of the air owing through the passage until the iirst mentioned valve is closed.

15. In a compressed air brake in combination with a main air pipe, an air reservoir and a brake cylinder; communication means connecting said main air pipe with the atmosphere and comprising a pressure chamber and means for restricting the venting of compressed air from said pressure chamber to the atmosphere, valve means connected with the main air pipe for locally venting compressed air from the main air pipe; actuating means for said valve means 1S connected with the main air pipe to hold said valve means normally closed; loading means for said actuating means to open said valve means upon a reduction of main air pipe pressure under the opposing effects of main air pipe pressure and of said loading means; a header unit comprising a normally closed valve connecting said air reservoir with the brake cylinder and coinprising actuating means for said valve connected with said pressure chamber and responsive to the pressure in the latter to open the valve of said header unit by the compressed air vented from the main air pipe to provide a supply of compressed air from said air reservoir to the brake cylinder when pressure drops in the main air pipe; a control unit comprising a normally open rst valve adapted to interrupt the flow of compressed air from said pressure chamber to the atmosphere, a second normally closed valve connecting the main air pipe with said pressure chamber, and actuating means for said rst and second valves operating the latter two valves upon a drop of pressure of a. predetermined amount in the main air pipe, to interrupt theventing of compressed air from the main air pipe by said first valve and to connect said actuating means of said header unit with the main air pipe.

16. In a compressed air brake having a brake cylinder, in combination, a triple valve having means regulating pressure in the brake cylinder in two different stages said means comprising a main actuating chamber and an auxiliary actuating chamber, means constituting a communication connecting said triple valve with the brake cylinder, adjustable means producing two different ow cross-sections in said communication, pneumatic actuating means for said adjustable means, said actuating means being connected with said auxiliary actuating chamber, valve means for selectively connecting said auxiliary actuating chamber and said actuating means with the main actuating chamber and the atmosphere, whereby the filling time period of the brake cylinder remains constant in both stages.

SIEGFRED KELLER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,031,213 Farmer Feb. 18, 1936 2,088,185 Borde July 27, 1937 2,173,928 Borde at al Sept. 26, 1937 2,094,173 Jack Sept. 28, 1937 2,278,700 Kaleshin Apr. 7, 1942 

